The ARINC 600 standard provides for avionics computers to be cooled using a current of cool air circulating under the computers. Each computer is allocated a portion of the total flow of this current of cool air, notably according to the power that it dissipates, in order to cool it. This cool air is injected into the computers via a bottom plate, commonly called “bottom cover”. This bottom plate is drilled with calibrated holes, each computer having to comply with constraints of head loss introduced on the current of cool air. The calibration of the holes and the range of head loss to be introduced are specified in the ARINC standard. Typically, for a level 2 ARINC computer, the head loss to be introduced must be between 200 pascals and 300 pascals.
Until today, almost no effort has been made to optimize the use of the stream of cool air injected into the onboard computers, notably because the power density dissipated by the electronic modules was not too high and because the constraints relating to the head loss introduced were not very difficult to observe. Currently, the power dissipated by the electronic modules contained in the onboard computers is increasing and their cooling is therefore becoming a matter of prime importance. Furthermore, the head loss constraints are also becoming more difficult to support, the tolerance range falling from 100 pascals to 50 pascals.
It has therefore become essential to seek to improve the effectiveness of the aeraulic cooling of the onboard computers, notably by focusing on the hot spots identified on the electronic modules and by optimizing the management of the injected air stream.
In the state of the art, baffles have been added inside the computers for this purpose, in order to deflect the cool air as a priority to the hot spots of the electronic modules. However, this technique is inadequate and it also introduces new mechanical stress problems.